1. Field of the Disclosure
The disclosure generally relates to a particulate composition formed from a conductive polymer (e.g., conductive polyanilines, polypyrroles, polythiophenes) bound to magnetic nanoparticles (e.g., Fe(II)- and/or Fe(III)-based ferromagnetic magnetic metal oxides). The particulate composition can be formed into a biologically enhanced, electrically active magnetic (BEAM) nanoparticle composition by further including a binding pair member (e.g., an antibody) bound to the conductive polymer of the particulate composition.
2. Brief Description of Related Technology
Polymers, once used for insulating purposes, have gained prominence for electrical conductivity, among other novel traits such as magnetism and biodegradability. The appellation “synthetic metals” has been duly given to these polymers that exemplify the conductive/magnetic properties of the metallic inorganics (e.g., iron), as well as the flexibility and lightness of plastics. Conducting polymers can be utilized in diverse areas ranging from corrosion protection to microwave shielding. Analytical chemistry and chemical/biological sensors are significant areas of applications as well. The conductive properties of the synthetic metals arise from the π-electron backbone and the single/double bonds of the π-conjugated system alternating down the polymer chain. Some conducting polymeric structures include polyaniline (PANi), polypyrrole, polyacetylene, and polyphenylene. Polyaniline, in particular, has been studied thoroughly because of its stability in fluid form, conductive properties, and strong bio-molecular interactions. Conductive polymers can be used in a biosensor, an analytical device capable of pathogen detection in which the conductive polymers act as electrochemical transducers to transform biological signals to electric signals that can be detected and quantified.
Detection technologies employing magnetic particles or microbeads have been used. These particles bind with the target analyte in a sample being tested, for example using a binding pair member specific to the target analyte, and are then typically isolated or separated out of solution magnetically. Once isolation has occurred, other testing may be conducted to detect the presence of analyte-bound particles. For example, various types of immunoassays based upon detecting a signal from a capture reagent are described in U.S. Pat. No. 5,620,845 to Gould et al.; U.S. Pat. No. 4,486,530 to David et al.; U.S. Pat. No. 5,559,041 to Kang et al.; U.S. Pat. No. 5,656,448 to Kang et al.; U.S. Pat. No. 5,728,587 to Kang et al.; U.S. Pat. No. 5,695,928 to Stewart et al.; U.S. Pat. No. 5,169,789 to Bernstein et al.; U.S. Pat. Nos. 5,177,014, 5,219,725, and 5,627,026 to O'Conner et al.; U.S. Pat. No. 5,976,896 to Kumar et al.; U.S. Pat. Nos. 4,939,096 and 4,965,187 to Tonelli; U.S. Pat. No. 5,256,372 to Brooks et al.; U.S. Pat. Nos. 5,166,078 and 5,356,785 to McMahon et al.; U.S. Pat. Nos. 5,726,010, 5,726,013, and 5,750,333 to Clark; U.S. Pat. Nos. 5,518,892, 5,753,456, and 5,620,895 to Naqui et al.; U.S. Pat. Nos. 5,700,655 and 5,985,594 to Croteau et al.; and U.S. Pat. No. 4,786,589 to Rounds et al. The aforementioned U.S. patents are hereby incorporated herein by reference herein in their entireties.
Statistics has shown that pathogens result in an estimated 14 million illnesses, 60,000 hospitalizations, 1,800 deaths, and cost approximately $2.9-$6.7 billion in the United States each year due to food-borne diseases (e.g., resulting from infection by Escherichia coli O157:H7). Furthermore, possible bioterror threats has presented urgent needs of biosensors for surveillance of foods to prevent the contamination of food supplies. Of these numerous food-borne pathogens, Bacillus cereus has garnered notice as bacteria that can cause two types of food poisoning: a diarrheal type, and an emetic type. The former leads to diarrhea while the latter results in vomiting. The ubiquitous nature of the Bacillus cereus pathogen is demonstrated by its status as a common soil saprophyte and association with foods, primarily plants, but also meats, eggs, and dairy products. It was implicated in a third of all cases of food poisoning in Norway (1988-1993), 47% in Iceland (1985-1992), and 22% in Finland (1992). Furthermore, recent research has concluded that Bacillus anthracis and Bacillus cereus are of the same species. B. anthracis is responsible for the lethal disease anthrax, an agent in biological terrorism/warfare. Thus, detection and defense against B. cereus may accurately model and lead to heightened security with respect to B. anthracis. 
Identification of pathogens by conventional methods, however, necessitates manual work and anywhere from 24 to 48 hours of incubation time. Thus, there exists a need for improved methods and compositions useful for the rapid, accurate, and selective detection of various pathogens.